<!DOCTYPE HTML>
<html>
<style type="text/css">
div {
  width: 64px;
  height: 64px;
  border: 64px solid blue;
}
</style>
  <body>
<div style="height: 0; border-bottom: 0; border-top-left-radius: 64px; border-top-right-radius: 64px;"></div>
<div style="height: 64px; border-width: 0 64px;"></div>
<div style="height: 0; border-top: 0; border-bottom-left-radius: 64px; border-bottom-right-radius: 64px;"></div>
  </body>
</html>
